Unavailability of Enough Water in the Indus River System 

The amount of water flowing through the River Indus has been a point of acute disagreement between the planners of KBD project and other impartial engineers.

To technically analyze the issue, the following table, from the year 1922 to 1991, indicates 69 years maximum flow pattern of the western rivers of Pakistan, measured at rim stations (Indus at KBD, Jehlum at Mangla & Chenab at Marala)

Reference: Surface Water Availability for Further Development, WAPDA, December 1994

From the table five parameters are evident

i. Maximum flow of the 3 western rivers 186.79 MAF evidenced in 1959-60

ii. Minimum flow of the 3 western rivers 100.31 MAF evidenced in 1974-75

iii. Average (per year) flow of the 3 western is 137.27 MAF

iv. 4 out 5 years flow of 3 western rivers is 123.59 MAF

A closer analysis of the flow pattern reveals that super floods occur approximately once in 5 years time, which may jack up the average flow to the respectable 137.27 MAF per year, but in the remaining four years, availability of water remain around 123.59 MAF only, or lower.

In all its calculations of the availability of water for KBD, WAPDA has insisted upon the average flow figures i.e. 137.27 MAF, whereas the criteria for designing a storage dam is of using the 4 out of 5 years flows, giving an 80% probability of water coming down the rivers to enable its storage. By adopting this criteria for our storage reservoirs, we end with a figure of 123.59 MAF available in our Indus River system.

 If in the above table of 69 years flow, the 9 years of exceptionally low flows of less than 120.0 MAF are disregarded, the next consecutive 2 years of low flows are 1931-32 (123.59 MAF) and 1932-33 (125.26 MAF), with an average of 124.4 MAF, which is very close to the 123.59 MAF, the figure of 4 out of 5 years water availability (80% probability flow).

 To support this theory, the US Supreme Court Ruling is " to be available in a practical sense the supply must be fairly dependable, storage dams cannot be filled on expectations of average flows which do not come, nor on recollections of unusual flows which have passed down the stream in previous year".

 Considering the Indus Water Apportionment Accord to be the benchmark, the simple and correct arithmetic of our water resources availability in the Indus River System should read as follows:

 Availability of Water in 3 Western Rivers (below rim station) 123.59 MAF

Requirement of the 4 Provinces (according to the Water Accord) 114.35 MAF

Release below Kotri (provisionally agreed in Water Accord) 10.00 MAF

 Remainder -0.76 MAF

The negative balance in the calculation shows that, there is virtually not enough water in River Indus, to be stored for usage in later part of any year. And if storage is tried, it will only be at the cost of the downstream riparian, depriving them of their legitimate rights of water use.

Contrary to realizing this fact, WAPDA has been publicizing the news of floods in River Indus and its breaching of protective bunds at various places, to try create a perception that enormous quantities of water go "waste" every year, and that if this water was stored in KBD, Pakistan would not only be saved from the damages of these high flows, but its agriculture would take a giant leap towards self-sufficiency. It has been argued that 34.84 MAF of water pass below the Kotri Barrage every year to the sea, and is therefore going waste.

To clarify the misconception of exceptionally high discharges of 34.84 MAF below Kotri, the following points needs to be closely followed:

1. At present all the barrages and the canals of Pakistan can take about 105 MAF against the allocated 114.35 MAF under the Indus Water Apportionment Accord 1991.
   The remaining 9.35 MAF ends up on its way to the sea through Kotri. And this will eliminate if the irrigation network is completed to accommodate this additional allocated flow.
2. Outflow from the eastern rivers of Sutlej, Beas and Ravi into Indus is about 6.97 MAF. Since all three rivers are committed to India, and with the progressive development going on in India, these flows will be reduced to zero (except in the few years of exceptionally high flood season flows), thereby reducing the Kotri discharges by that amount.
3. As per the Indus Water Treaty, India has also been given an unrestricted use of water to cultivate 1343477 acres from the western rivers, in addition to all the rights of eastern river. India, to date, has utilized 6.75 MAF and will draw another 4.79 MAF from the system, to further reduce the flows at Kotri by that amount.
4. The 34.83 MAF flow to sea is in fact the mean discharge, and is bound to be lower by 10.0 to 14 MAF in any specific year.

 The correct calculations in this respect will be:

Waste flows below Kotri Barrage = 34.84 MAF

Less

i. Additional allocations under Indus Water Accord 1991 = 9.35 MAF

ii. India’s flow in the Eastern Rivers = 6.97 MAF

iii. India additional water rights under the Indus Water Treaty = 4.79 MAF

iv. Yearly flow under Kotri barrage (lower by14 MAF than average) = 14.0 MAF

Net available flow below Kotri Barrage = - 0.27 MAF

Hence, the net available water to flow to the sea reduces to a negative balance, leaving nothing for storage into KBD. Therefore, the news of floods "wasting enormous amount of water" does not hold true

Still for people, who consider the flood water to be a mere waste do not realize that there is no mechanical method of removing millions of tons of deposited silt from the river beds of the barrages, and it is the force of water from these high floods that helps in washing away much of the accumulated silt.

References:

KBD; The Sindh Case by Kazi Abrar, 1998

Look before you leap by Abdul Majeed Kazi & A.N.G Abbassi